DESCRIPTION

The above functions are character classification utility functions, for
use with wide characters (wchar_t or wint_t). See the description for
the similarly-named single byte classification functions (such as
isalnum(3)), for details.
Extended locale versions of these functions are documented in
iswalnum_l(3). See xlocale(3) for more information.

RETURN VALUES

The functions return zero if the character tests false and return non-
zero if the character tests true.